The AARP is taking over New Orleans for the weekend as national politicians, celebrities and thousands of conventioneers start descending on the city today.

More than 20,000 attendees from across the country will meet at AARP's Expo for three days of volunteering, entertainment and information, all tailored to the interests of the 50+ audience.

Kelly Shultz with the New Orleans Convention and Visitor's Bureau says the AARP's Life@50+ is expected to generate an estimated $23.5 million in economic impact to the city of New Orleans.

And she says once all the celebrities start blogging and tweeting, the publicity for the city will be priceless.

The event kicks off on today with "New Orleans Reimagined," a day of service led by AARP Ambassadors, including CBS's Sports' James Brown, Dan Marino and Martina Navratilova. Organizers say more than 1,500 volunteers will visit over 25 community locations to offer service and support to the New Orleans community.

Attendees will also experience lifestyle and education sessions led by celebrities and subject experts, fitness classes, cooking demonstrations, hands-on technology classes, cultural events, live entertainment, health screenings and music classes.

As part of the event, AARP will host its annual "Movies for Grownups" Film Festival, featuring some of this season's greatest films, along with a few films that attendees will get the opportunity to see before they open in theaters. Actor Billy Crystal will be on hand Friday night to introduce his upcoming film Parental Guidance at a special screening, and 50 lucky attendees will have the chance to meet him.

A special showcase, "Health Innovation @50+ Live Pitch," will connect health technology startups with investors in an effort to stimulate innovations that serve the health needs of Americans age 50+.

And the Expo will wrap on Saturday with a one-night-only special concert event at the New Orleans Arena featuring Grammy Award-winning vocalists Stevie Nicks, Gladys Knight and Melissa Etheridge. (Tickets are available for purchase at Ticketmaster.)

President Barack Obama and Vice Presidential Nominee Paul Ryan will address the AARP members at Life@50+ in New Orleans on Friday, Sept. 21st.

The President will speak live, via satellite, at 10:45 a.m. according to organizers and Chairman Ryan will speak live in the convention center at 11:30 a.m.

Because of these appearances they say, the opening show with Hoda Kotb and Lagasse will be moved to 8:30 a.m. on Friday.

Both President Obama and Vice Presidential Nominee Ryan's sessions are not open to the general public. You must be an AARP member registered for Life@50+ to attend the sessions.